Plumb-bob



Patented May l6, I899.

I. A. MARTIN.

' PLUMB 808.

(Application filed Apr. 30, 1898.)

INVENTOH @M. W BY NITED STATES PATENT OFFICE.

ISAAC A. MARTIN, OF OURAY, COLORADO.

'PLUMB-BOB.

SPECIFICATION forming part of Letters Patent N0. 625,181, dated May 16, 1899.

Application filed April 30, 1898.

To all whom it may concern.-

Be it known that I, IsAAo A. MARTIN, of Ouray, in the county of Ouray and State of Colorado, have invented a new and Improved Plumb-Bob, of which the following is a full, clear, and exact description.

My invention relates to an improvement in plumb-bobs such as are used for surveying purposes; and it consists in a novel construction by which the suspending-cord may be drawn within the bob or extended, as desired.

The invention also consists of the novel features of construction by which this result is obtained, as will be particularly described and claimed hereinafter.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the figures.

Figure l is a cross-sectional elevation of my improved bob. Fig. 2 is a similar View taken at right angles to that of Fig. 1. Fig. 3 is a cross-section taken upon the line 3 3 of Fig. 1. Fig. 4 is a top plan view of the bob with the cap removed, and Fig. 5 is a perspective view of the plate upon which the mechanism is mounted.

In using plumb-bobs in surveyingit is often desired to be able to quickly shorten or lengthen the suspending-cord. To secure this result, I have provided a cavity within the bob, within which is placed a reel adapted to receive the cord and a coiled spring connected with said reel, so as to wind the cord thereon.

The bob is formed in two parts-the body A, which comprises all the lower or conical portion of the bob, and the cap B, which is joined to the body by means of threadedflanges, as shown at a in Figs. 1 and 2. The cap is provided with a central hole B? of such size as to closely embrace the suspendingcord 0. The two parts of the bob are hollowed, so as to form a cavity B, which is partly within the bodyand partly within the cap ofthe bob. This cavity may, however, be formed either in both parts of the bob or in one only. Within this cavity is a plate E, which is adapted to be' supported upon the body A of the bob at a slight distance above the bottom of the cavity. This plate is provided with two upturned standards 6 and e,

$erial No. 679,357. (No model.)

adapted to receive the journals of the reelD. These standards are preferably formed by being stamped out of the plate and then bent upward. The standard 6 is provided with a hole for-receiving one end of the reel-shaft, and the standard 6' is provided with a slot reaching to the upper end thereof and adapted to receive the other end of the reel-shaft. This permits the ready insertion or removal of the shaft from the standards. The end of the shaft which lies within the slot is held in place bya plate c which embraces the shaft and is secured to the upper ends of the standard c. This plate may be secured in place by screws or any other convenient means.

Beneath the plate E is mounted a coiled spring J. One end of this spring is secured to a shaft K, which is fixed at its upper end to the center of the plate E and which at its lower end preferably enters a socket formed in the body A. This spring is surrounded by a cap or casing I, which is journaled upon the lower portion of the shaft K and which has its upper edge provided with teeth, forming a crown-gear, as clearly shown in Figs. 1, 2, and 3.

Upon one end of the reel-shaft is mounted a pinion F, and upon the standard at the same end is mounted an idler-gear F,which meshes with the pinion F and also with the crowngear upon the cap or casing I. Upon the op posite end of the reel-shaft is mounted apinion G, and this pinion is engaged by a catchlever H, which is pivoted upon the plate E, and is held upward into engagement with the gear G by a spring H also mounted upon the plate E.

The catch-lever H has one arm projecting upward close to the outer wall of the cavity B and is engaged by a pin 72., which extends through the wall of the bob and is adapted to be engaged by the hand. When this pin is pressed inward, the catch-lever H is freed from the gear G and the reel is free to turn in either direction. When the catch-lever H is freed from the gear, the spring J, acting through the train of gears, will rotate the reel D, so as to wind the cord 0 thereon. If,how-

ever, the cord C be pulled outward, it may be unwound when the catch H is released. By this means the length of cord which extends outward from the plumb-bob may be adjusted at will and very readily. This is a matter of great convenience, as it enables the bob to be carried in the pocket from one set up to another, or when not in use suspended close under the tripod, and yet enables any length of cord desired to be obtained at once.

Having thus fully described my invention, I claim as new and desire to secure by Letters Patent- 1. A plumb-bob,formed in two parts,abody and a cap uniting on horizontal lines, said parts being hollowed to form a-cavity therein, and the cap having a central hole therethrough for the passage of the suspendingcord, a plate having up-bent arms forming reel supporting standards and supported above the bottom of the cavity, a central shaft secured to and projecting below said plate, a coiled spring beneath said plate having one end secured to said shaft, a casing or cap inclosing said spring and attached to its free end, the rim of said casing having teeth forming a crown-gear, a reel mounted to turn in the standards, a pinion on the drum-shaft, an idler-wheel meshing with the pinion and crown-gear,a spring-h eld catch for said drum, and a releasing-pin therefor projecting outside the bob, substantially as described.

2. A plumb-bob formed in two parts attachable to each other and having a cavity formed between, and a central hole for the passage of the suspending-cord, a frame insertible in said cavity consisting of a plate having upturned standards and having a central post fixedly secured thereto and projecting below the frame, a spiral spring beneath the frame and secured by its inner end to said post, a cup journaled upon the post and inclosing thespring, the upper edge of the cup being toothed and the outer end of the spring being secured to the cup to rotate it, a reel journaled in the standards above the plate, gears connecting the reel and the teeth upon the cup,and a lock adapted to lock the reel against turning.

3. A plumb-bob formed in two parts attachable to each other, having a cavity formed between and a central hole for the passage of the suspending-cord, a frame slidable in said cavity and consisting of a plate having upturned standards and having a central post fixedly secured thereto and projecting below the frame, a spiral spring beneath the frame and secured by its inner end to said post, a cup journaled upon the post and encircling the spring, the upper edge of the cup being toothed and the outer end of the spring being secured. to the cup to rotate it, a reel journaled in the standards and above the frame, gears connecting the reel and the teeth upon the cup, a catch or locking lever pivoted upon the frame and engaging a pinion, a springsecured to the frame and holding the catch in engagement and a pin passing through the wall of the cavity and engaging said catchlever to free it from the pinion.

ISAAC A. MARTIN.

Witnesses:

W. J. BENTON, W. W. CHAPMAN. 

